Azo dyestuffs



Patented Dec. 26, 1950 AZO DYESTUFFS Mordecai Mendoza, Blackley, Manchester, England, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing. Application August 22, 1949, Serial No. 111,771. In Great Britain September 8,

3 Claims. (01. 260-173) This invention relates to new azo dyestuffs and more particularly to new trisazo dyestuffs for leather.

According to my invention I provide a process for the manufacture of new azo dyestuffs which comprises coupling in alkaline medium two molecular proportions of diazotised 4-nitro-4'- amino-diphenylamine-2-sulphonic acid with the monoazo compound obtained by coupling in acid medium one molecular proportion of a diazotisd l-(mor p-aminobenzoyl)amino-8-naphtholmono-, or di-sulphonic acid which is unsubstituted in the 7-position, with one molecular proportion of a m-aminophenol or a m-diamine of the benzene series which is capable of coupling twice.

The diazotised 4-nitro-4-amino-dinhenylamine-Z-sulphonic acid is believed to Couple with the monoazo compound both in the *I-eosition of the napht alene nucleus and also in the benzene nucleus which is attached to the azo linkage.

The diazotisation and coupling proc sses and the isolation of the dyestuif may be carried out by the conventional methods normally used for dyestuffs of this kind.

As exam les of l-(mor p-aminobenzoyD- amino-S-naphthol-monoor di-sulphonic ac ds there may be mention d l-(4-aminohenzovl) amino-8-naphthol-3:G-disulphonic acid, 1-03- aminoben oyhamino 8 nanhthol--sdnhonic acid, l-(3'-aminobenzoyl) amino 8 nachthol- 3:6-dis 1ohonic acid, and the corresponding 4:6-disulphonic acid, and as examples of m-diamin s there may be mentioned m-phenyl- SOsH wherein A is the radical mass. addition of sufficientcrushed ice and the cooled wherein X is a radical selected from the group consisting of H and CH3, and wherein Y is a radical selected from the group consisting of NI-Iz and OH and wherein Z is a radical selected from the group consisting of H and SOsH.

The invention is illustrated but not limited by the following examples in which the parts are by weight:

Example 1 43.8 parts of l-(4'-aminobenzoyl) amino-8,- naphthol-3:G-disulphonic acid are dissolved in 300 parts of water containing 8 parts of caustic soda. The solution so obtained is stirred and 6.9 parts of sodium nitrite in the form of a 20% aqueous solution are added. The mixture is then added dropwise, at a temperature not exceeding 10 (3., to a stirred solution of 30 parts of strong hydrochloric acid (d=l.16) in parts of water. The diazo compound separates as a light red hrown precipitate. The suspension is allowed to stir for a further 1 hour to complete the formation of the diazo compound. A solution of 10.8 parts of m-phenylene diamine in 150 parts of water containing 15 parts of strong hydrochloric acid (d=l.l6) is then added in a steady stream. The mixture is stirred for 16 hours to complete the coupling and the monoazo compound is obtained in the form of a dark red-brown preci'oitate. The precipitate is dissolved by adding suilicient caustic soda solution to make the reaction mixture slightly alkaline and 80 parts of soda as are then added. 61.8 parts of 4-nitro- 4-amino-dipl enylamine-Z-sulphonic acid are dissolved in 1000 parts of water at 80 C. contaf'n ng S?ffifil91ll7 soda ash to make th: solution faintl a kaline. 16.8 parts of sodium nitrite in the form of a 20% aq eous solution are added to the hot solution and the mixture is stirred until the temperature falls to C. parts of strong hydrochloric acid (d=l.l6) are then quickly added and the r;su1ting diazo compound is preci itated as a greyish-green gelatinous The mixture is cooled to 10 C., by the diazo pa te is then added to the alkaline solution of the above monoazo compound. The reaction mixture is stirrcd for a further six hours and the new trisazo dyestufi is then precipitated from the dark brown solution by adding suflicient salt to make a 20% brine, heating to C. and. then acidifying with strong hydrochloric acid. The dyestuff is then filtered off, dried and ground. It forms a blackish-brown powder which is readily soluble in water to give a deep brown solution. It dyes leathers of all tannages in level nigger brown shades of good all-round fastness properties and shows extremely good build up properties. If 1-(3'-aminobenzoyl) amino-8-naphthol-3:G-disulphonic acid is substituted for the isomeric compound used above there is'obtained adyestufi which yields greener and duller tones of nigger brown and which possesses similar good fastness properties. This latter dyestufi may be described by the following structural formula:

e -Q E A S 0 3H- S 0 3H NH:

wherein A is the radical QNHTOAML SOsH If 1 (3' aminobenzoyl)amino-naphthol-416- disulphonic acid is used, the dyestuff obtained gives slightly redder and brighter shades.

The dyestuff obtained in the above example when utilizing 1 (4 aminobenzoyD'amino-ilnaphthol-3zfi-disulph'onic acid may be structurallyshown by the following formula:

wherein A'is the radical SOaH Example 2 The diazo derivative obtained as described in Example 1 from 43.8 parts of l-(4-amino- 'benzoyl) amino-8-naphthol-3 fi-disulphonic acid is combined with 10.9 parts of m-amino-phenol dissolved in 150 parts of water containing 15 parts of strong hydrochloric acid (d=1.16) and the resulting monoazo compound is further coupled with the diazo derivative obtained from 61.8 parts of -4-nitro l'-amino-diphenylamine-2-sulphonic acid. The trisazo dyestuff thus obtained is isolated as described in Example 1. It yields redder shades on leather than the product of Example 1 and possesses equally good dyeing and fastness properties.

Example 3 Example 4 35.8 parts of l-(3-aminobenzoyl) amino-8- naphthol4-sulphonic acid are dissolved in 300 parts of water containing 4 parts of caustic soda. The solution is stirred and 6.9 parts of sodium nitrite are added as a 20% aqueous solution. The mixture is then added dropwise at a temperature not exceeding 10 C., to a stirred mixture or" 30 parts of strong hydrochloric acid (cl=1.16) and 50 parts or" Water. To the resulting red-brown diazo suspension there is added a solution of 10.8 parts of m-phenylene diamine in parts of water containing 15 parts of strong hydrochloric acid (d=1.l6) and the mixture is stirred for 16 hours to complete the coupling. The monoazo compound so formed is then further coupled with the diazo derivative obtained from 61.8 parts or" l-nitrol-amino-diphenylamine-Z-sulphonic acid by the method described in Example 1/ The trisazo dyestuir obtained dyes leather in nigger brown shades.

I claim:

1. A20 dyestuffs of the formula H X OH IIIHC O N=N -NH A A Y ZN wherein A is the radical SOaH wherein X is a radical selected from the group consisting of H and CH3, wherein Y is a radical selected from the group consisting of NH2 and OH and wherein Z is a radical selected from the group consisting of H and 5031-1.

2. The azo dyestufi of the formula SOaH wherein A is the radical 3. The azo dyestufi which in acid form has the formula so an wherein A is the radical SOQH MORDECAI MENDOZA.

No references cited. 

1. AZO DYESTUFFS OF THE FORMULA 